Whatever you do, don't lose the black one. NLA, and it is a completely custom part for the 931 S2. There's nothing wrong with the one in your photo. The cutouts are to clear the mounting bolts for the TPS on the bottom side of the throttle body.

From memory, the red o-ring that goes on the throttle body itself is common to the same vintage 911 Turbo (930 I think), so it is still available. Part number 999.701.477.40, $5. PM if interested.

The gasket is part number 931.110.152.01. It is included in the 931 head gasket kit, but is hard to get by itself. I might have a spare or two in my stash. I'm also working with a local resource to reproduce several of the gaskets that are NLA independently, and this one has already been scanned, test, cut, and ready for production. So we can have one of these for you regardless within a couple of weeks (pricing to be determined). List price on the gasket is $10.50._________________15 981 GTS | 88 924S SE | 82 931 Holbert | 82 931 Rallye | 81 937 | 81 Euro 931 | 81 Weissach | 80 US 928 | 80 US 931 '941' | 80 US 931 | 80 931 GTR | 79 Sebring | 78 D-Prod Replica | 78 w/D-Prod kit | 78 Poli-Form | 78 Limited Edition | 77 Martini

I recently checked with my local Porsche dealer and that gasket which goes between the lower and upper charge tube is actually still available out of Germany._________________81 RED 931 S2(daily driver),81 WHITE 931 S2(not currently drivable).
Cincinnati,Ohio